Pixel-aligned is an object level property, which enables
an object to have its vertical and horizontal paths aligned to the
pixel grid. This property remains with the object when the object
is modified. Any vertical or horizontal path in the object gets
aligned to pixel grid as long as the property is set for it.

An illustration showing pixel-aligned objects and objects
that are not pixel-aligned

Aligning new objects to pixel grid

The Align New Objects to Pixel Grid option is available
in the Advanced section of the New Document dialog box.

This option is also available in the Transform panel menu (flyout
menu) of the Transform panel.

Align New Objects to Pixel Grid option in the Transform panel
menu

If you enable this option, any new objects that you draw have
the pixel-aligned property set by default. For new documents created
using the web document profile, this option is enabled by default.

The crisp appearance of pixel-aligned strokes is maintained in
the raster output at a resolution of 72-ppi only. For other resolutions,
there is a high possibility of such strokes producing anti-aliased
results.

Objects that are pixel-aligned, but do not have any straight
vertical or horizontal segments, are not modified to align to the
pixel grid. For example, because a rotated rectangle does not have
straight vertical or horizontal segments, it is not nudged to produce
crisp paths, when the pixel-aligned property is set for it.

Note:

The document level property and pixel-aligned status of each
object are saved in the .ai file.

Aligning existing objects to pixel
grid

An object with the Align to Pixel Grid option selected,
is nudged to align to pixel grid whenever it is modified. For example,
if you move or transform a pixel-aligned object, the object is realigned
to pixel grid according to its new coordinates.

To align an existing object to pixel grid, select the object
and check the Align to Pixel Grid check box at the bottom on the
Transform panel.

Align to Pixel Grid option in the Transform panel

When you select this option, the vertical and horizontal segments
of the paths of the object are nudged. As a result, the appearance
of such segments always shows crisp strokes, for all stroke widths
and all locations. Objects with this option selected, always have
stroke widths in full integer values.

Bringing non-aligned objects into documents with the Align New
Objects to Pixel Grid option enabled, does not automatically pixel-align
such objects. To make such objects pixel-aligned, select the object
and then select the Align to Pixel Grid option from the Transform
panel. You cannot pixel-align objects such as rasters, raster effects,
and text objects because such objects do not have real paths.

Selecting objects not aligned to
pixel grid

Aligning symbols to pixel grid

To create a pixel-aligned symbol, select the Align to Pixel
Grid option from the Symbol Options dialog box. Symbols aligned
to pixel grid remain aligned to the pixel grid at all locations
of the artboard, in their actual size.

Note:

A scaled symbol may not produce crisp paths although it is
pixel-aligned by property.

Saving selected slices

Anti-aliasing options

Text anti-aliasing

The Character panel in Illustrator provides the following
text anti-aliasing options:

None

Sharp

Crisp

Strong

Text anti-aliasing options in the Character panel

You can set anti-aliasing options for each text frame. These
text anti-aliasing attributes get saved as part of the document.
These options are also supported for PDF, AIT, and EPS formats.
Text anti-aliasing options can be exported to or imported from PSD.

While exporting to BMP, PNG, Targa, JPEG, or TIFF formats the
following options are available in the anti-aliasing drop-down list:
None, Art Optimized and Type Optimized.

Art optimized option produces raster for each of these
formats in the same way as in earlier versions. However, text anti-aliasing
options are not honored while rasterizing the artwork in this case.